Implementation of the Lupus Low Disease Activity State in Pediatric Rheumatology Care: The Role of the Visual Analog Scale.

Abstract

We compared the measurement properties of a traditional physician global assessment of disease activity (PhGA) 10-cm visual analog scale (PhGA0-10) with that of the three-point numeric scale (PhGA0-3) in childhood-onset systemic lupus erythematosus (cSLE) as part of the childhood Lupus Low Disease Activity State (cLLDAS). We used a secondary data analysis from a convenience sample of 100 patients with cSLE followed every three months for up to seven visits. Ratings of PhGA0-10, PhGA0-3, parent assessment of patient well-being (ParGA) (range: 0= very poorly, 10 = very well), disease activity as measured by the SLE disease activity index 2000 (SLEDAI-2k), Safety of Estrogens in Lupus Erythematosus National Assessment (SELENA) SLEDAI, and the British Isles International Lupus Activity Group index (BILAG; A = 9, B = 3, C = 1, D/E = 0) were compared. After linear transformation of PhGA0-10 to a 0 to 3 range (tPhGA0-10), the frequency of PhGA0-3 ≤1 was assessed to estimate the impact of scale type on the scoring of the cLLDAS. In 600 visits, the median (range) scores of PhGA0-10, PhGA0-3, SLEDAI-2k, SELENA-SLEDAI, and BILAG were 2 (0-10), 1(0-3), 4 (0-28), 4 (0-32), and 2 (0-28), respectively. PhGA0-10 and PhGA0-3 ratings were strong to moderately correlated with (r = 0.73; P < 0.0001) and with more variability for PhGA0-3 ≥2. SELENA-SLEDAI and SLEDAI-2k scores were moderately correlated with PhGA0-10 (r = 0.56/0.54; P < 0.0001). ParGA values were weakly correlated with all other measures considered (all r = -0.19 to -0.34). There were 490 of 600 visits with PhGA0-3 ≤1 and 497 of 600 visits with tPhGA0-10 ≤1 (κ (SE) =0.59 (0.04), McNemar P = 0.4). PhGA0-3 and PhGA0-10 have comparable measurement properties and yield almost identical cLLDAS rates when used in cSLE.